ON THE LICHEN-GONIDIA QUESTION. 
267 
A few years previous to this, however, instigated no doubt 
by the researches of Cohn, a microscopist of the first order, who 
in 1852 indicated the production of zoospores in the gonidia, 
or at least in Protococcus , which he supposed might come 
from lichen thalli, certain collateral investigations had been 
made by Famintzin and Baranetsky. The results of these were 
recorded in several continental journals, e. g. “ Mem. de l’Acad. 
imp. Sc. St. Petersbourg,” 1867, and Melang. “Biol. Bull, de 
l’Acad. de St. Petersbourg,” 1868. Having obtained chloro- 
phyllaceous gonidia from the genera Physcia , Premia, and 
Cladonia, they succeeded in cultivating them independently of 
the lichens themselves. According to their report some of 
these, as those of Physcia parietina , produced zoospores, while 
others continued to increase by vegetative growth. These 
free gonidia they concluded were identical with the genus 
Cystococcus, Naeg., which is thus not an independent alga, but 
only a phase of the gonidia of the lichens under review. So 
also with respect to the phycochromaceous gonidia obtained 
from Collema and Peltigera similarly cultivated, they found that 
these were capable of maintaining an independent life, and in 
some cases were identical with so-called algals. Hence they 
concluded that these free-living gonidia ought to be omitted 
from the list of algse. Somewhat similar experiments were 
subsequently made by Woronin ( vid . “ Ann. des. Sc. Nat. ” ser. v. 
t. xvi. p. 317) on Physcia parietina and Ph. pulverulenta , but 
in neither case was any lichen-thallus produced. Bornet also 
attempted the cultivation of spores and algse together, and in 
his memoir gives details of the experiment in which he was 
most successful, where some spores of Physcia parietina 
were sown upon a layer of Protococcus viridis . (Termination 
of the spores took place some days subsequently, and they put 
forth radicle filaments, which speedily elongating and ramifying, 
wherever they came in contact with the cells of the Protococcus, 
adhered either directly or by a lateral branch, the filament in 
either case being applied closely to the gonidium and surround- 
ing it [see our Plate, fig. 5], He adds that if the presence of 
the spores still adherent did not show the true nature of these 
radicles, it would be impossible to distinguish the gonidiiferous 
filaments from the adult lichen. All other experiments, 
however, of this kind, are certainly, in so far, at least, as the 
amount of labour expended, and the variety of methods 
adopted, and the apparent care taken to ensure success, com- 
pletely cast into the shade by those of Dr. Treub. A short 
notice by him in “ Lichenencultur,” in 66 Bot. Zeit.,” Nov. 1873, 
was followed immediately afterwards by a lengthened memoir, 
entitled 66 Onderzoekingen over de Natuur der Lichenen,” 
Leiden, Nov. 1873. In the second section of this he gives a 
